1. Field of the Description
The present description relates, in general, to the illusion of three dimensional (3D) image generation and projection, and, more particularly, to systems and methods using a varifocal beamsplitter to produce 3D images or depth and space illusions (e.g., real volumetric images that protrude into the viewer space or side of mirror/glass) without requiring viewers to wear 3D glasses or the like.
2. Relevant Background
There is a growing trend toward using 3D projection techniques in theatres and in home entertainment systems including video games and computer-based displays. In many conventional 3D projection techniques, the right eye and the left eye images are delivered separately to display the same scene or images from separate perspectives so that a viewer sees a three dimensional composite, e.g., certain characters or objects appear nearer than the screen and other appear farther away than the screen. However, stereoscopy, stereoscopic imaging, 3D imaging, and volumetric display are labels for any technique capable of creating the illusion of depth in an image.
Often, the illusion of depth in a photograph, movie, or other two-dimensional image is created by presenting a slightly different image to each eye or the creation of parallax. In most animated 3D projection systems, depth perception in the brain is achieved by providing two different images to the viewer's eyes representing two perspectives of the same object with a minor deviation similar to the perspectives that both eyes naturally receive in binocular vision.
There is a continuous desire and need to provide new techniques that provide cost effective but eye-catching content with depth and dimension. For example, it is desirable to grab the attention of crowds in shopping malls, on busy streets, in amusement parks, and other crowded facilities such as airports and entertainment arenas. As discussed above, 3D imagery and volumetric displays are exciting ways to appeal to viewers and hold their attention. However, the use of 3D imagery has, in the past, been limited by a number of issues. Typically, 3D projection technologies require the viewer to wear special viewing glasses. This is often inconvenient for many applications and can significantly add to costs to provide the 3D media for projection and also for the special eyewear that has to be provided to the viewer.
Some attempts have been made in providing volumetric displays without the need for eyewear, but these have not been widely adopted as each has its own limitations. For example, FIG. 1 illustrates a volumetric display 100 that makes use of a vibrating reflective mirror (comprised of an aluminized Mylar® sheet or the like). As shown, the display 100 includes a membrane mirror 110 that is attached to an acoustical driver 120 in the form of a subwoofer of a loudspeaker, and the membrane mirror 110 vibrates 115 as shown to provide a varifocal mirror.
An image 130 is displayed in multiple planes to a viewer 160 as the vibrating membrane mirror 110 reflects a 2D image projected or provided by an oscilloscope or cathode ray display 170. As shown, the sequence of planar objects of the displayed image 130 has volume and appears to be in a position behind the mirror 110 (i.e., is a virtual image 135). The varifocal mirror 110 affects optical translation of the 2D image from display 170 to form a volume.
Systems similar to display 100 suffer from a number of shortcomings. The use of an acoustic driver or speaker 120 results in the acoustic power or sound to be radiated out into the viewing area or to the viewer 160, which creates a large amount of unwanted noise and requires significant driving power. The solid driver 120 (e.g., a subwoofer) does not allow beamsplitting such that the mirror 110 has to be fully reflective. Therefore, the viewer 160 must look at the mirror 110 off axis to see the monitor 170. Even when the monitor 170 is off axis, at some point when the viewer 160 moves the monitor 170 will obstruct their view. Further, the system 100 can only provide a virtual image as shown at 135 to be recessed into the display apparatus 100 (e.g., the image 130 viewed by the viewer 160 appears to be a distance behind the vibrating mirror 110 as is typical for conventional mirrors). The primary image generator was a single display 170, which inextricably and undesirably linked image resolution and display rendering (e.g., speed).
Due to the shortcomings of such volumetric displays, there remains a need for systems and methods for providing 3D or volumetric displays in a cost effective manner and without the need for special eye or head wear.